Visual Web Development

Transcription

1 Martin Rowe, Terry Marris October 2007 Visual Web Development 7 Contact We see how users may us without exposing our address to spiders and robots that crawl through the web looking for addresses to add to spammer's lists. We use your computer as a relay that hands s on to a server. 7.1 Contact Form The user is invited to provide their address, name and a comment. They then click either the send button to submit the form, or the clear button to clear the form. 1

2 7.2 Installing the SMTP Service To send from an ASP.NET application you must have the Simple Mail Transfer Protocol (SMTP) service of the Internet Information Services (IIS) installed and configured. This may already be done at college. But at home installing ASP.NET directly from Microsoft does not automatically install SMTP. The details shown below may differ slightly depending on whether you are using Windows XP with the Classic Windows layout scheme. You will need Administrator rights. Installing SMTP Service 1. Start, Settings, Control Panel, Add or Remove Programs, Add/Remove Windows Components 2. Internet Information Services (IIS), Details, SMTP Service, OK 3. Next. Insert Windows XP disk if requested and follow instructions 4. Finish 2

3 Configuring SMTP Service 1. Start, Run, inetmgr, OK 2. Expand local computer 3. Right-click Default STMP Virtual Server, Properties 4. Access, Relay 5. Select Only the list below 6. Add, Single Computer 7. IP address: OK 3

4 7.2 The Code Behind the Send Button The code shown below sends an from your web page. Protected Sub btnsend_click(byval sender As Object, ByVal e As System.EventArgs) Handles btnsend.click Dim strfrom As String = txt .text Dim strname As String = txtname.text Details from the client Dim strmessage As String = txtmessage.text Dim strsubject As String = "Enquiry" Dim strto As String = "tmarris@lec.ac.uk" Replace my with your address Dim strhost As String = "localhost" Dim intport As Integer = 25 Your computer forwards the Dim server As New System.Net.Mail.SmtpClient(strHost, intport) Dim As New System.Net.Mail.MailMessage(strFrom, strto, strsubject, strmessage) server.send( ) End Sub We: collect the input from the user specify the subject and delivery address specify that it is our own computer that relays the create a SmtpClient object from the given relay computer details create a MailMessage object send a Send( ) message to the server object: server. Send ( ) the receiver the message The object receiving the message looks down its list of methods: if it finds one that corresponds with the message, it performs its task. If the receiver does not find a corresponding method, it complains. 4

5 7.3 Use Case Use Case Contact Goal to send the contents of a form completed by the user as an to the owner of the web page Pre-condition Post-condition Initiating Actor the user Main Success Scenario 1 system displays prompts 2 user enters their address, name and message 3 system sends the message to the owner of the web page 4 exit success The pre- and post- conditions, and exceptions, are left as an exercise for you to complete. 7.4 Layout, Properties and Values 5

6 Control Property Value Form File Name Contact.aspx Title Contact Document Title Contact Label ID lbltitle Text Contact Us Font Size xx-large ForeColor blue Label ID lbl Text Your ? Text Box ID txt Label ID lblname Text Your name? Text Box ID txtname Label ID lblmessage Text Your message? Text Box ID txtmessage Rows 5 Text Mode Multiline Button ID btnsend Text Send Button ID btnclear Text Clear Notice: the font is specified to be Arial throughout. Arial (or Verdana) is the font of choice because it is the easiest to read on a screen. What fonts do Google and Microsoft use for their screen displays? the text box ID = txtmessage is a multi-line text box allowing the user to enter more than one line of text as a single item. 6

7 7.5 Exercise 1. Implement the program, shown above, that sends an to you at your e- mail address 2. Investigate any exceptions that might occur and update the use case table shown above 3. Modify the program you wrote for Exercise 1 above so that control is maintained in the event of any possible errors. 7